SU1513415A1 - Positional control system - Google Patents

Abstract

The invention relates to metallurgy and mechanical engineering and can be used to control the position of the pressure screws of rolling mills. The purpose of the invention is to increase speed and reduce system oscillation. The goal is achieved due to the fact that the input signal of the system is compared with the output signal of the second integrator and the square root is extracted from the resulting difference. The result is compared in the comparator with the output signal of the first integrator and the result obtained is fed to the input of the first integrator and from its output to the input of the second integrator. The output of the second integrator is fed to the input of the position controller, which is compared with the output of the position sensor and summed with the outputs of the comparator and the first integrator. The output of the position controller is compared in the speed controller with the output of the speed sensor and summed with the output signal of the comparator. The output of the speed controller is amplified, limited and compared in the current sensor with the output signal of the current sensor, the output signal of the current controller is amplified in power and fed to the input of the motor. The outputs of the speed controller and the limiter amplifier are compared and fed to the input of a threshold device, the output of which is fed to the control inputs of keys that disable the input of the first integrator from the output of the comparator and the input of the second integrator from the output of the first integrator. PI-regulating units are used as regulators. 5 il.

Description

The invention relates to the field of metallurgy and mechanical engineering and can be used to control the position of the pressure screws of rolling mills.

The aim of the invention is to increase the speed and reduce the oscillation of the system.

FIG. 1 is a block diagram of the system; in fig. 2 and 3 - diagrams

ten

31513415

changes in the signals of the driver when the system is operating according to triangular and trapezoidal tachograms, respectively; in fig. 4 and 5 are graphs of transient processes in the system during the development of a given displacement in the absence of current limiting and its presence, respectively.

The system contains a driver 1, an input source 2, a nonlinear block 3, a comparator 4, the first key 5, the first integrator 6, the second key 7, the second integrator 8,

: contour regulation circuit 9, position regulator 10, speed regulator 11, limiting amplifier 12.

: current regulator 13, power amplifier 14, executive motor 15, current sensors 16, speeds 17 and positions 18, comparison unit 19, module allocation section 20, comparator 21, reference source 22, threshold device 23.

FIG. 2-5 shows x; (t) - output signal of the i-ro block; K, is the transmission coefficient of the position sensor 18; epj ,, Cp - the initial and final position of the shaft of the engine 15; x - the amplitude of the output signal of the compara- 30 x. and the negative feedback signal

generates a signal x Xg -sign (Xj-x which, with closed keys 5 and 7, is transformed by the first integrator

5b to the impact of Xg) dt, having the shape of a triangle (Fig. 2) or a trapezium (Fig. 3), depending on whether the signals Xj and x reach the level of limitation Xjjj

and the second integrator 8 - in the signal t

Xg Kg / x (t) dt, varying from the level Xg (0) Kdp cfH to the level AH to the areas where | xg (t) (x is parabolic, and in areas where / Xg (t) j., linear (Fig. 2). The signal x- (t) is,, o

the main control action for the position control loop 9, and the signals Xg (t) and x, (t), which are proportional to the first and second derivatives of this effect, are used to create parallel corrective connections along the back channel, allowing for increased speed system in start-up mode.

The position controller 10 converts the control actions Xd, x.

five

torus 4j Xgg- maximum amplitude of the output signal of integrator 6; G3 (t) is the rotation speed of the engine 15 shaft; I (t) is the motor current 15; itpg - specified movement; utf (t) - with the current position of the engine 15 shaft; Max is the maximum value of the motor current 15.

Relay blocks 1, square-root extraction block Z can be used as a non-linear block.

The system works as follows.

In order to move the motor shaft 15 from a certain initial set position (to the final (j) output signal of the input source 2, it is necessary to change it abruptly by the value x () D

bond by position x

18

 TO

in si

Cash task speed x. The speed controller 11 converts the signal X, 0, the corrective control effect x and the negative feedback signal on the speed CO of the motors 15, K. p co in input sig

40

X 1 for the amplifier-limiter 12,

Limiter 12 generates a signal

.one

45

X

41

X

Ota

-X

012

if X

if X

if X

one

(I

and

X

01g

B x

 -X

  (

Oii

Cd | - the transmission coefficient of the position sensor 18. Unit 3 performs the function of extracting the square root of the difference between the output signals of the source 2 of the input signal and the second integrator 8, generates a signal X, ,,, (x and limits the output signal of the first integrator 6 to the level X (, g оэ- Comparator 4

50

D (g CAT l (ax) is the level of the signal which is not limited to the current I; K is the gain of the current sensor 1;

 maximum permissible current of the motor core 15. Comparison unit 19 forms at its output the difference of signals x

and x, 2. t4 na Block 20 of the modulus of the module determines the absolute value of this difference Hus / x,) /,

x and the negative feedback signal

generates a signal x Xg -sign (Xj-x); which, with closed keys 5 and 7, is transformed by the first integrator

b to the impact of Xg) dt, having the shape of a triangle (Fig. 2) or a trapezium (Fig. 3), depending on whether the signals Xj and x reach the level of limitation Xjjj

and the second integrator 8 - in the signal t

Xg Kg / x (t) dt, varying from the level Xg (0) Kdp cfH to the level AH to the areas where | xg (t) (x is parabolic, and in areas where / Xg (t) j., linear (Fig. 2). The signal x- (t) is,, o

the main control action for the control loop 9 is the position, and the signals Xg (t) and x, (t), proportional to the first and second derivatives of this effect, are used to create parallel corrective connections on the reference channel, which allow to increase the system speed in the start-up brake modes.

The 10 position controller transforms the control actions Xd, x.

bond by position x

18

 TO

in the task speed signal x. The speed controller 11 converts the signal X, 0, the corrective control action x and the negative feedback signal on the speed CO of the engine 15, K. p co in input sig

X 1 for the amplifier-limiter 12,

Limiter 12 generates a signal

if X

one

X

01g

.one

five

X

Ota

-X

012

if X

if X

(I

and

B x

 -X

  (one )

Oii

0

D (g CAT L) (ax the level of the signal for setting the current I; K is the gain of the current sensor 16;

 the maximum permissible current of kory is the motor 15.; Comparison unit 19 generates at its output a difference of signals x

and x, 2. t4 on Block 20 The modulus determines the absolute value of this difference: Hus / x,) /, and

515134

the second comparator 21 converts it into a control signal, keys 5 and 7

Xg1 XQ, signCx Q-x.),

where the reference signal produced by the source 22 of a single signal, is a device such as a source of reference voltage. The reference signal source 22 is necessary so that when O, the comparator 21 produces a signal x corresponding to the closed state of the control keys 5 and 7,

Regulators of position 10 and velocity 11 are usually made proportional or proportional integral, depending on the requirements of the institute for the system. If they have proportional characteristics, then their output and input signals are related to each other by equations

| x, o (xd + K, -x, g)

- x, 7) Crc,

the gains of the position and velocity controls, respectively;

transmission coefficients for parallel corrective communication signals.

If the speed controller 11 has a proportional integral characteristic, its output signal should be limited to prevent an excessive increase in the integral component of its output voltage in the current limiting mode. The signal value x, must be selected from the condition of a reliable change in the state of the comparator 21 in this mode

- X

0 (1

x

22

(3)

A proportional current regulator 13 converts the difference between the setpoint signals for current x and feedback current x, g K. into a signal sent by power amplifier 14, generating a control signal, 4 by motor 15, under the action of this signal in the engine core circuit 15 a current is flowing I,

10 15

156.

creating in the excited engine 15 an electromagnetic moment M C I, as a result of which the engine 15 rotates at a speed

 C1 (|): ms,

C0 (t)

where I is the moment of inertia of the engine 15; Mj, is the moment of static resistance on the engine 15 shaft;

C is a proportionality coefficient between current I and moment Mj. As long as the condition

0

M, (C G

(four)

five

0

five

0

five

 t. P)

with max - -.

where jj is the desired acceleration of the engine 15, which is determined by the setting of the blocks of the driver 1,

limiting amplifier 12 running

in the linear zone, t, e.

х х „. (5)

Therefore, the output signals b .. for T9 comparisons, x "-. and block 20 of the modulus xj | x (equal to zero, and the second comparator 21, under the influence of a small reference signal x., is in a state in which the control keys 5 and 7 are closed (xxxg sign ( x.) the system fulfills the specified displacement 6 (3 - C (, (Fig. A).

As the static moment increases, M. on the motor shaft 15 to such an extent that condition (4) becomes unfair, the acceleration of the engine 15 decreases (), the resulting input signals from position controllers 10 and speed 11 increase, which leads to saturation of the amplifier-limiter 12 and transition of the system to current limiting mode. This mode may also occur at the beginning of the process of changing the driver, when the motor 15, even at the maximum permissible current T, does not rotate (CO 0), due to the fact that, as a result of the amplifier 12, equality (5) is violated (equation (1)) Signals appear at the outputs of comparator unit 19 and module elimination unit 20. At xx the state of the comparator 21 is changed,,

15

which leads to the opening of controlled Clusters 5 and 7 and the cessation of growth, control signals x, and x-

about 8

the outputs of the integrators 6 and 8 of the driver 1. Due to this, after the system leaves the current-limiting mode, the oscillations around the steady-state position w (Fig. 5) are tested. ten

These distinctive features allow to increase the speed and reduce the oscillation of my system, i.e. allow any input signals to be traversed

without overshooting and dotting, the reliability of the installations, in which the system is applied, is impacted. so as oscillations of the system around the steady state can lead to an abnormal example.

driven nut screw. of the rolling mill, the task for moving the upper roll, down -j

while the rolled metal is still in the cage, which leads to a stop mode. This is done to improve the metal structure of the tail part of the ingot .. Ec20

thirty

If the control system does not prevent you from watching the measures for eliminating the oscillating drive around the steady-state values when leaving the stop mode, then a heavy accident may occur after the ingot is thrown out of the stand: roll roll-on.

Claims (1)

Invention Formula A position control system containing series-connected5 0 0 0 five 0 An input source, a naty-nep unit and a co-switch connected by the output to the first inputs of the speed controller and a position controller connected by the second input to the output of the first integrator and the second input of the comparator, the third input to the output of the second integrator and the second input nonlinear unit, the fourth input - with the output of the position sensor, and the output - with the second input of the speed controller connected by the third input to the output of the speed sensor, and the current regulator, power amplifier and controller connected in series a supporting motor, the shaft of which is kinematically connected with the shafts of the position and speed sensors, and the electrical output of which is connected to the input of the current sensor connected by the output to the first input of the current regulator, which differs from. By the fact that, in order to increase speed and reduce the oscillation of the system, a comparison block, a threshold device, two keys and an amplifier-limiter connected by the input to the output of the speed controller and the first input of the Compare block, and the output to the second inputs current regulator and comparison unit connected by the output through the threshold device to the control inputs of both keys, the information input of the first key is connected to the output of the comparator, and the output is connected to the input of the first, the integrator connected Odio to ikforma- ipioHHOMy input of the second, connected by an output to the input of the second II-integrator. -tf (i I Xf / y sect l / ", / 5; / w f-l ff 12 (-} H / 3 (Rig.1 W .g 1 (/ 1 xm Editor And, Shulla Compiled by G. Nefedova Tehred L. Oliynyk Proof-reader S. Cherni Order 6076/46 Circulation 788 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Xjt Fy m Fig.b Subscription